The objective of this proposal is to analyze the neuroprotective effect of an 7 nAChR agonist in an in vitro model of excitotoxicity and in an in vivo model that mimics glaucoma-like conditions. In culture studies, rat retinas obtained from Long Evans rats will be enzymatically dissociated and cultured using various concentrations of the agonist for different amounts of time to analyze neuroprotection against glutamate-induced excitotoxicity. After various times in culture, RGCs will be fluorescently immunostained using an antibody against Thy 1.1. RGC survival will be quantified and compared to control untreated conditions to determine any significant differences between the two populations. In vivo studies will induce glaucoma-like conditions in Long Evans rats using the hypertonic saline model, where 2M hypertonic saline is injected into episcleral veins to decrease the drainage through the trabecular meshwork, resulting in a slow increase in intraocular pressure, the primary risk factor associated with glaucoma. To determine if the 7 nAChR agonist can prevent the loss of RGCs normally associated with performing this procedure, 5 l of various concentrations of 7 nAChR agonist will be directly injected into the vitreous humour of a Long Evans rat's right eye at various time points before injecting hypertonic saline to induce glaucoma-like conditions. After one month, rats will be euthanized, retinas will be removed, flat mounted, fixed and nuclei in the RGC layer will be stained with cresyl violet to assess general damage in the layer or RGCs will be immunostained with an antibody against Thy 1.1. Stained nuclei in the RGC layer and stained RGCs in experimental retinas will be counted and compared to counts obtained from untreated retinas from the same animal that represent an internal control for each experiment. The results from these studies could lead to a preventative treatment of glaucoma that does not involve lowering intraocular pressure. PUBLIC HEALTH RELEVANCE: The objective of this proposal is to analyze the neuroprotective and/or preventative effect of an 7 nAChR agonist in an in vitro model of excitotoxicity and in an in vivo model that mimics glaucoma-like conditions. In rat culture studies, the 7 nAChR agonist will be used to analyze neuroprotection against glutamate-induced excitotoxicity in rat retina. Under in vivo conditions, the 7 nAChR agonist will be injected into the posterior chamber of the eye before inducing glaucoma-like conditions. The results from these studies could lead to a preventative treatment of glaucoma.